Contact David Rempel for more information or to join this Technical Committee
Email: david.rempel@ucsf.edu

Objectives

To collect, review and share with all ergonomists and OSH in the world, methods, “best” practices and “best experiences” for risk assessment and management of WMSDs, including aspects related to job/task design and to workplace/work tools design.

Musculoskeletal Disorder (MSD) Risk Assessment Tools

A number of risk assessment tools have been developed to quantifying workplace biomechanical and psychosocial factors that may be predictive of MSDs. The MSD Technical Committee has developed a list of tools that have publications in peer-reviewed scientific journals of (1) reliability and (2) predictive value. The tools are listed in categories and then alphabetically. The MSD TC welcomes suggestions for changes to this list and additional references.

The OWAS method was developed by a Finnish steel company of Ovako Oy and is based on ratings of working postures and load: 4 postures for the back, 3 for the arms, and 7 for the lower limbs, and 3 levels for the weight of load handled or amount of force used. Values from the 4 factors are combined to assess 4 categories of risk and recommended actions.

category 1: normal postures, which do not need any special attention;

category 2: postures must be considered during the next regular check of working methods;

General description: Direct observations at the workplace are made in real time using a portable personal or hand-held computer and data are accessible for immediate analysis and presentation. Duration and number of events are calculated for postures related to 4 body regions (arms, neck, trunk and knee) as well as for manual handling.

General Description: QEC assesses biomechanical exposures to 4 body regions and allows physical work activities to be assessed in collaboration with the worker. It was designed to be fast, easy to use and not require extensive training. A one-page assessment sheet includes questions for both the practitioner (observer) and the worker to quantify exposures. The exposure levels for four main areas of the body can be scored and these can form a basis for intervention and re-assessment.

The TLV for Hand Activity assesses biomechanical risk to the distal upper extremities and is intended for ‘mono-task’ jobs performed for 4 or more hours per day. The TLV combines 2 factors: (1) average hand activity level based on the frequency of hand exertions and the duty cycle, and (2) normalized peak hand force. Both are scaled from 0-10. The TLV identifies an Action Level (caution) and a higher Threshold Limit Value (immediate action recommended). [Modifications to the Hand Activity are proposed in the 2017 TLV Book based on recent prospective studies]

The OCRA method estimates risk to the upper extremities for repetitive tasks and includes the biomechanical factors of frequency, excessive use of force, awkward upper limb movements and postures, insufficient recovery periods, and net duration of the repetitive tasks.

Description:
ISO 11228-3. Annex C. 2014.

Occhipinti, E. (1998). OCRA: a concise index for the assessment of exposure to repetitive movements of the upper limbs. Ergonomics, 41, 9,1290-1311.

RULA is a postural targeting method for estimating the postural risks of upper extremity disorders. It uses a graphical approach requiring regular or random sampling of observations to develop a visual distribution of posture.

The Strain Index estimates biomechanical risk for distal upper extremity disorders (e.g., hand, wrist, forearm and elbow). A job is divided into tasks. For each task and for each hand, 6 job biomechanical factors are classified into categories of exposure by an observer. A datasheet is used to combine the levels in the categories into an overall risk score, the Strain Index. Updated as Revised Strain Index (RSI) in 2016 with descriptions of Composite Strain Index (COSI) and Cumulative Strain Index (CUSI) for complex tasks.

The TLV for upper limb localized fatigue is designed to prevent excessive or persistent upper limb (forearm, elbow, shoulder) musculoskeletal fatigue for repetitive work. The TLV curve is based on the force exerted at a % strength (% maximum voluntary contraction (%MVC)) and the duty cycle of work (e.g., the % of time that applied force is greater than 5% MVC). The TLV is based on psychophysical, laboratory, and epidemiologic studies.

The Lumbar Motion Monitor (LMM) is a device that is carried on the back of a worker, like a backpack, and continuously measures the position, velocity, and acceleration of the spine in the sagittal, lateral, and twisting planes. A model was developed to use this data to estimate risk for low back disorders (LBDs).

The RNLE is a risk-assessment tool to assess the manual material handling risks associated with lifting and lowering tasks. An equation is used to assess job task variables to determine the Recommended Weight Limit (RWL), a maximum acceptable weight (load) that nearly all healthy employees could lift over the course of an 8 hour shift without increasing the risk low back disorders (LBDs). In addition, a Lifting Index (LI) can be calculated to provide a relative estimate of risk of the existing load versus the RWL. RNLE has been enlarged to analyze cumulative exposure and multi-task jobs (composite, variable and sequential).

Psychophysical theory examines the relationship between the strength of a perceived sensation (S) and the intensity of a physical stimulus (I). This theory has been used in manual materials handling tasks to establish the maximum acceptable weight or force for a wide variety of lifting, lowering, pushing and pulling tasks (among others). Liberty Mutual Insurance Company has published comprehensive tables for this type of strength assessment.

The LiFFT estimates a “daily dose” of cumulative loading on the low back using fatigue failure principles. Three variables are necessary to derive the cumulative load associated with a lifting task: the load weight, the maximum horizontal distance from the spine to the load, and the number of repetitions for tasks performed during the workday. For multiple lifting tasks, the cumulative damage estimate for each can be summed together to estimate the cumulative daily spine load. LiFFT can be downloaded at: http://eng.auburn.edu/research/centers/occupational-safety-ergonomics-injury-prevention/index.html

The effort-reward imbalance model aims to support the understanding of how social and psychological factors contribute to injury and disease. The construct is based on “social reciprocity” and the theory that failed reciprocity resulting from high effort with low rewards will elicit negative emotions and sustained stress responses. Conversely, appropriate social rewards will promote wellbeing health and survival. Rewards are characterized by financial, esteem and career opportunities, including job security. There are 3 psychometric scales assessed including effort, reward and over commitment. There are 2 versions of the ERI questionnaire including a long version (23 Likert scaled items) and the short version (16 items), more commonly used in large epidemiological studies.

The Copenhagen Psychosocial Questionnaire was developed to provide work environment professionals and researchers a standardized and validated questionnaire to assess a variety of psychosocial factors. There is now a second version and, like the first version, the COPSOQII has 3 versions of differing lengths, the longest of which is recommended for researchers and the shortest version recommended for the workplace. The COPSOQII assesses work demands, organization, work relationships and leadership, the work-individual relationship, health and well-being, personality, and offensive behaviors.

This model predicts that mental strain results from the interaction of job demands and job decision latitude. The combination of low decision latitude and heavy job demand has been associated with mental strain. and job dissatisfaction. The JCQ is designed to measure scales assessing psychological demands, decision latitude, social support, physical demands, and job insecurity.